The Nernst Equation
Nernst Equation
The Nernst Equation is the mathematical tool used to calculate the actual electrode potential (
) of a half-cell or overall cell potential ( ) under non standard conditions.
General Nernst Equation
Where,
= Electrode potential under non-standard conditions (V) = Standard Electrode Potential (V). = Ideal gas constant ( ). = Thermodynamic temperature (K) = The number of moles of electrons transferred in the half-reaction. = Faraday’s constant ( )
Simplified Nernst Equation (
Simplified Nernst Equation
The syllabus explicitly mentions knowledge of the simplified Nernst Equation, in which the thermodynamic temperature
is taken to be constant at room temperature ( ) and the is replaced by :
Derivation of Simplified Nernst Equation
Using laws of logarithms:
Substituting this conversion and
and in the general Nernst Equation:
Concentration of Solids and Gases
Concentration of Solids and Gases
The concentration of pure solids, pure liquids, and standard gases is defined as constant (1)
Therefore the concentrations of solids and gases are set to
.